1. Technical Field
The present invention relates to an electronic device, an organic electroluminescence device, and an organic thin film semiconductor device, and in particular to a sealing technology for an electronic device equipped with an organic semiconductor element, an oxide semiconductor element, or an organic electroluminescence element.
2. Related Art
In recent years, portable equipment such as a mobile phone or a PDA, or a personal computer using a low profile display such as an organic electroluminescence (hereinafter also referred to simply as EL) display device or an electrophoretic display device as a display section thereof has been developed. An organic EL display device is provided with a number of light emitting elements on the surface of the substrate, and performs desired display by independently controlling driving of each of the light emitting elements. Further, it has been considered to form an electrophoretic display device by combining an active matrix substrate provided with organic thin film transistors (hereinafter abbreviated as TFT) with, for example, electrophoretic elements. As described above, organic EL elements and organic TFT are thought to be promising as devices for displays, and in particular, since devices using organic materials can be formed at relatively low temperature, plastic substrate can be used therefor, thus possibilities as flexible elements are expected.
However, such organic devices have had a significant problem regarding reliability. In the case with an organic EL display device, for example, it is well known that the light emitting sections described above are deteriorated by oxygen and moisture, and accordingly, a highly airtight structure capable of preventing penetration of oxygen and moisture has been required. Further, it is required riot only to prevent oxygen and moisture from penetrating for the outside but also to encapsulate a getter agent (e.g., a desiccating agent or an oxygen absorbing agent) for capturing a small amount of oxygen and moisture penetrating therein. In other words, the sealing structure alone is not sufficient for improving the reliability, and without any means for capturing the penetrating harmful components, the effects of providing the sealing structure do not last long. An example of an organic EL display device having a getter agent inside the space hermetically sealed by a sealing substrate is disclosed in, for example, JP-A-2000-208252 and Japanese Patent No. 2,686,169.
Further, regarding an organic TFT, there have been some cases in which, although they have operated stably in vacuum or in an inert gas atmosphere, the characteristics thereof have been deteriorated when they have been exposed to the atmosphere including oxygen and moisture. Therefore, as is the case with organic EL display devices, the sealing structure and the capturing means for the harmful components have been required.
As described above, organic EL elements and organic TFT are preferable for manufacturing flexible elements taking an advantage that they can be manufactured at relatively low temperature. However, the problem of reliability arises here again. In other words, if a glass substrate is used as the substrate of the device side, glass or metal can also be used as the material for the sealing structure (a substrate for sealing). In this case, highly airtight sealing structure can be realized. On the contrary, in the case in which a plastic substrate is used as the substrate of the device side, if glass or metal is used as the material of the sealing structure, flexible devices can hardly be realized, and accordingly, the use of the plastic substrate becomes meaningless. Therefore, although in this case, plastic is inevitably used in the sealing structure side, it is quite difficult to realize such a highly airtight sealing structure with plastic material. Specifically, although it has been proposed to seal an organic device with a resin film, an inorganic film, or a multilayered structure thereof, the gas permeabilities of these materials are significantly large in comparison with those of the glass and metal, and accordingly sealing might be insufficient. Further, if the capturing means such as a getter agent is provided, it reaches its capture limit in a relatively short period of time, thus making its practical application difficult.